1. Technical Field of the Invention
This invention relates to the manufacture of alcohols. More particularly, this invention relates to a method for the preparation of primary branched alcohols from certain normal hydrocarbons and formaldehyde in the presence of free radical initiators. The product alcohols are obtained as a mixture of species which can have one more carbon atom than the starting material. These alcohols may be used as intermediates for the production of detergents and plasticizers and as solvents.
2. Information Disclosure Statement
Among the many alcohols of commercial significance, fatty alcohols and their derivatives are of great importance as surfactants, plasticizers and as intermediates for the production of monomers, polymers, lubricating oils and the like. The most widely used are the fatty alcohols having from 12 to 15 carbon atoms. The "detergent" alcohols are defined by the Chemical Economics Handbook, Alcohols, 609.5021G (SRI Intl.1987) as alcohols having twelve or more carbon atoms and having a carbon backbone with a "high degree of linearity". This is a convenient category for such alcohols, since they are used primarily in detergent applications (although also used in a number of diverse applications) and alcohols having less than twelve carbons are used to a greater extent in other products and are often referred to as "plasticizer" alcohols. Highly branched alcohols having more than twelve carbons are also excluded. Alcohols derived from animal fats and vegetable oils have carbon backbones that are completely linear, but those derived from ethylene and n-paraffins may range from 35 to 99 percent linear. However, the types and levels of branching still permit the use of such alcohols in most detergent applications. Plasticizer alcohols, i.e. the primary aliphatic alcohols having from 4 to 13 carbons (excluding the linear versions with 12 or 13 carbons) are discussed in the Chemical Economics Handbook, Id. at 609.4021C.
There are many methods known in the art for the preparation of alcohols. See Buehler and Pearson, Survey of Organic Synthesis Wiley Interscience, New York, 174, (1970). For example, solvolysis of esters, halides, xanthates, amines, cyclic ethers etc. produce a variety of alcohols. These alcohols always contain the same number of carbon atoms as the starting material. This can be represented by the following equation: ##STR1##
Paraffinic hydrocarbons such as n-dodecane can be converted to corresponding straight-chain alcohols by direct oxidation, as described by I]am et al. in "Liquid-Phase Oxidation of n-Dodecane in the Presence of Boron Compounds", Ind. Eng. Chem. Prod. Res. Dev.", Vol. 20, pp. 315-19 (1981).
It is known to prepare alcohols which contain one carbon more than the starting material by hydroformylation (the oxo process) of olefins. This process is not new in the art and can be represented as follows: ##STR2##
Formaldehyde may be added to olefins to form alcohols with one more carbon than the starting olefin (Arundale and Mikeska, Chem. Rev., Vol. 51, pp. 505, 506 and 528-39, (1952). ##STR3##
Oyama discloses the reaction of primary and secondary alcohols with formaldehyde in the presence of free radical generators to produce glycols in J. Orq. Chem., Vol. 30, pp. 2429-32 (1965). Kollar in U.S. Pat. No. 4,337,371 disclosed a method for the preparation of ethylene glycol wherein methanol and formaldehyde are reacted in the presence of an organic peroxide and water to form ethylene glycol. Yeakey and Applicant Sanderson disclose in coassigned U.S. Pat. No. 4,550,184 a method for the preparation of 2-hydroxymethyl-l,3-dioxolane from 1,3-dioxolane and formaldehyde in the presence of an organic peroxide. See also coassigned U.S. Pat. No. 4,628,108, in which an ionizable metal salt is used in conjunction with the organic peroxide. An article by Sanderson et al., "Free Radicals in Organic Synthesis. A Novel Synthesis of Ethylene Glycol Based on Formaldehyde," J. Org. Chem., Vol. 52, pp. 3243-46 (1987), discloses the reaction of 1,3-dioxolane with formaldehyde in the presence of free radical initiators to form an intermediate which can be catalytically hydrogenated to ethylene glycol.
U.S. Pat. No. 2,818,440 discloses processes for additions of methylol groups to saturated hydrocarbons, including linear paraffins and cycloparaffins, which employ formaldehyde and organic peroxides. The methylol group can be added to an internal carbon of a linear paraffin. In the preferred mode, a saturated organic compound such as a paraffin or cycloparaffin is in a liquid phase in which the peroxide is dissolved, while the formaldehyde is present in a separate, generally aqueous, liquid phase. Alternatively, gaseous formaldehyde can be added to such a liquid organic phase in the reactor. See Rust et al., "Free Radical Addition of Cyclopentane and Cyclohexane to Formaldehyde", J. American Chem. Soc. Vol. 80, pp. 6148-49 (1958).
Despite the various routes described and the ones which have been devised, there is still a need for a method for producing primary branched alcohols from readily available but non-reactive normal hydrocarbons such as n-alkanes.
Additionally, it would be an advance in the art to prepare branched alcohols from normal hydrocarbons.